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Dual Functional S-Doped g-C3N4 Pinhole Porous Nanosheets for Selective Fluorescence Sensing of Ag+ and Visible-Light Photocatalysis of Dyes
摘要： This study explores the facile, template-free synthesis of S-doped g-C3N4 pinhole nanosheets (SCNPNS) with porous structure for fluorescence sensing of Ag+ ions and visible-light photocatalysis of dyes. As-synthesized SCNPNS samples were characterized by various analytical tools such as XRD, FT-IR, TEM, BET, XPS, and UV–vis spectroscopy. At optimal conditions, the detection linear range for Ag+ was found to be from 0 to 1000 nM, showing the limit of detection (LOD) of 57 nM. The SCNPNS exhibited highly sensitive and selective detection of Ag+ due to a significant fluorescence quenching via photo-induced electron transfer through Ag+–SCNPNS complex. Moreover, the SCNPNS exhibited 90% degradation for cationic methylene blue (MB) dye within 180 min under visible light. The enhanced photocatalytic activity of the SCNPNS was attributed to its negative zeta potential for electrostatic interaction with cationic dyes, and the pinhole porous structure can provide more active sites which can induce faster transport of the charge carrier over the surface. Our SCNPNS is proposed as an environmental safety tool due to several advantages, such as low cost, facile preparation, selective recognition of Ag+ ions, and efficient photocatalytic degradation of cationic dyes under visible light.
关键词： cationic dyes,pinhole porous nanosheet,photocatalytic degradation,visible light,Ag+ ions,S-doped g-C3N4,fluorescence sensing
更新于2025-09-19 17:15:36
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Photochemistry and Photophysics - Fundamentals to Applications || Catalytic Degradation of Organic Dyes in Aqueous Medium
摘要： Water pollution by the textile industry is an emerging issue. Textile industry is the major industrial sector which contributes to water pollution. Textile industry releases a huge amount of unfixed dyes in wastewater effluents. About 20% of the dye production all over the world is discharged as waste in industrial effluents by textile industry. These dyes are highly stable and colored substances which disturb the aqueous ecosystem significantly. Therefore, there is a need for methods to remove organic dyes from textile industrial effluents. Photocatalysis and catalytic wet oxidation are best practices for degradation of dyes in wastewater. In photocatalysis, the dye molecules can be completely degraded into inorganic non-toxic compounds by irradiation of the dye solution under visible or ultra-violet light in the presence of semiconductor metal-oxide photocatalysts. In catalytic wet oxidation, various metal-based catalysts in supported or unsupported form can be used as heterogeneous catalysts for degradation of dyes in the presence of oxygen or hydrogen peroxide. These processes have several preferences like easy separation of the catalyst from reaction mixture and recycling of the catalyst.
关键词： degradation,Langmuir-Hinshelwood mechanism,dyes,catalysis
更新于2025-09-19 17:15:36
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On the impact of competing intra- and intermolecular triplet-state quenching on photobleaching and photoswitching kinetics of organic fluorophores
摘要： While buffer cocktails remain the most commonly used method for photostabilization and photoswitching of fluorescent markers, intramolecular triplet-state quenchers emerge as an alternative strategy to impart fluorophores with 'self-healing' or even functional properties such as photoswitching. In this contribution, we evaluated combinations of both approaches and show that inter- and intramolecular triplet-state quenching processes compete with each other. We find that although the rate of triplet-state quenching is additive, the photostability is limited by the faster pathway. Often intramolecular processes dominate the photophysical situation for combinations of covalently-linked and solution-based photostabilizers and photoswitching agents. Furthermore we show that intramolecular photostabilizers can protect fluorophores from reversible off-switching events caused by solution-additives, which was previously misinterpreted as photobleaching. Our studies also provide practical guidance for usage of photostabilizer–dye conjugates for STORM-type super-resolution microscopy permitting the exploitation of their improved photophysics for increased spatio-temporal resolution. Finally, we provide evidence that the biochemical environment, e.g., proximity of aromatic amino-acids such as tryptophan, reduces the photostabilization efficiency of commonly used buffer cocktails. Not only have our results important implications for a deeper mechanistic understanding of self-healing dyes, but they will provide a general framework to select label positions for optimal and reproducible photostability or photoswitching kinetics in different biochemical environments.
关键词： photoswitching,intramolecular quenching,self-healing dyes,super-resolution microscopy,intermolecular quenching,photostabilization,fluorophores,triplet-state quenching,STORM
更新于2025-09-19 17:15:36
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Colorimetric Polymerase Chain Reaction Enabled by a Fast Light-Activated Substrate Chromogenic Detection Platform
摘要： Miniaturization of nucleic acid tests (NATs) into portable, inexpensive detection platforms may aid disease diagnosis in point-of-care (POC) settings. Colorimetric signals are ideal readouts for portable NATs, and it remains of high demand to develop color readouts that are simple, quantitative and versatile. Thus motivated, we report a Fast Light-Activated Substrate cHromogenic polymerase chain reaction (FLASH PCR) that uses DNA intercalating dyes (DIDs) to enable colorimetric nucleic acid detection and quantification. The FLASH system is established on our finding that DID-DNA intercalation can promote the rapid photooxidation of chromogenic substrates through light-induced production of singlet oxygen. Using this principle, we have successfully converted DID-based fluorescent PCR assays into colorimetric FLASH PCR. To demonstrate the practical applicability of FLASH PCR to POC diagnosis, we also fabricated two readout platforms, including a portable electronic FLASH reader and a paper-based FLASH strip. Using the FLASH reader, we were able to detect as low as 60 copies of DNA standards, a limit of detection (LOD) comparable with commercial quantitative PCR. The FLASH strip further enables the reader-free detection of PCR amplicons by converting the colorimetric signal into the visual measurement of distance as a readout. Finally, the practical applicability of the FLASH PCR was demonstrated by the detection and/or quantification of nucleic acid markers in diverse clinical and biological samples.
关键词： FLASH,Singlet Oxygen,Photooxidation,DNA Intercalating Dyes,Colorimetric,Nucleic Acid Tests,Paper-based Strip,Point-of-Care,Portable Electronic Reader,Polymerase Chain Reaction
更新于2025-09-19 17:13:59
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High-quality quantum dots for multiplexed bioimaging: A critical review
摘要： Bioimaging carried out using two or more fluorophores possessing different emission wavelength can be termed as a multicolor/multiplexed bioimaging technique. Traditionally, images are captured sequentially using multiple fluorophores having specific excitation and emission. For this purpose, multifunctional nanoprobes, such as organic fluorophores, metallic nanoparticles, semiconductor quantum dots, and carbon dots (CDs) are used. Among these fluorophores, quantum dots (QDs) have emerged as an ideal probe for multiplexed bioimaging due to their unique property of size tunable emission. However, the usage of quantum dots in bioimaging is limited due to their toxicity. Furthermore, the reproducibility of optical properties is cynical. These desirable properties, along with enhancement in quantum efficiency, photostability, fluorescence lifetime, etc. can be achieved using precision control over synthesis parameters. This review summarizes the desirable properties and synthesis methods of such superior QDs followed by their application in multiplexed imaging.
关键词： Multiplexed Imaging,Quantum dots,Microreactor,Bioimaging,Organic Dyes
更新于2025-09-19 17:13:59
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A series of aromatric-amine-cored fluorescent emitters for amplified spontaneous laser emission and emission turn-on sensing
摘要： In this paper, five boron dipyrromethene dyes were designed with aromatric-amine-cored structure. Their molecular structure and photophysical performance were discussed in detail in various solvents. It was found that these five dyes were highly fluorescent ones in toluene with emission quantum yield higher than 95%. Amplified spontaneous emission (ASE) performance of these fluorescent dyes was then analyzed in toluene. Efficient and promising ASE spectra peaking at ~545 nm were observed for four of these fluorescent dyes with full width at half maximum value of ~5 nm and ASE efficiency up to 9%. It was confirmed that aromatric-amine-cored structure was positive to improve ASE performance. The reason for ASE missing in one of these fluorescent dyes was revealed as the vibrational relaxation of its N-H group. In solvent MeCN, however, this dye showed an interesting phenomenon, emission turn on effect towards Hg(II). Its sensing performance and sensing mechanism were discussed in detail as well. Good linear response and high selectivity were found for both colorimetric sensing and emission turn on sensing.
关键词： ASE,emission turn on,laser dyes,optical sensing
更新于2025-09-19 17:13:59
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Effect of fluoro-substituted acceptor-based ancillary ligands on the photocurrent and photovoltage in dye-sensitized solar cells
摘要： Herein, we report four novel heteroleptic ruthenium (II) complexes, namely SD-7 to SD-10, containing fluoro- and trifluoro- methyl antennas as substituents on the ancillary ligands for dye-sensitized solar cells, and were compared to the benchmark dye N719. Photosensitizers (dyes) SD-7 to SD-10 were synthesized according to a typical one-pot three-step procedure with the corresponding ancillary ligands (LS-7 to LS-10). All the dyes were characterized by ATR-FTIR, 1H NMR and mass spectrometry. Furthermore, the photophysical, electrochemical and photovoltaic performances were compared with N719. The band gaps, ground and excited state oxidation potentials were measured. The photovoltaic performance of the dyes showed that SD-7 with five fluorine atoms and SD-8 with eCF3 at the –ortho position of the phenyl moiety outperformed the benchmark dye N719 with the efficiencies of 8.03% and 8.17%, respectively, with current density of 19.57 and 19.46 mA?cm?2, respectively, and open-circuit voltages of 0.65 V and 0.69 V, respectively, under optimized conditions. The fabricated solar devices at lab-scale showed a systematic trend of decreasing JSC when the fluoro-substituted dyes were sensitized on TiO2: SD-7 (with five –F) > SD-8 (with one eCF3 at ortho position) > SD-9 (with one eCF3 at para position) > SD-10 (with two eCF3, one at ortho and one at para position). This can be attributed to the greater number of fluorine atoms directly attached to sp2 hybridized carbon atoms, which greatly enhanced the dipole moment and intimate electronic coupling of SD-7 with TiO2 nanoparticles leading to better photocurrent density.
关键词： Fluoro-based dyes,Acceptor-based ancillary ligand,Photovoltaic performance,Dye-sensitized solar cells,Ruthenium complex
更新于2025-09-19 17:13:59
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Surface passivation of zero-mode waveguide nanostructures: benchmarking protocols and fluorescent labels
摘要： Zero mode waveguide (ZMW) nanoapertures efficiently confine the light down to the nanometer scale and overcome the diffraction limit in single molecule fluorescence analysis. However, unwanted adhesion of the fluorescent molecules on the ZMW surface can severely hamper the experiments. therefore a proper surface passivation is required for ZMWs, but information is currently lacking on both the nature of the adhesion phenomenon and the optimization of the different passivation protocols. Here we monitor the influence of the fluorescent dye (Alexa Fluor 546 and 647, Atto 550 and 647N) on the non-specific adhesion of double stranded DNA molecule. We show that the nonspecific adhesion of DNA double strands onto the ZMW surface is directly mediated by the organic fluorescent dye being used, as Atto 550 and Atto 647N show a pronounced tendency to adhere to the ZMW while the Alexa Fluor 546 and 647 are remarkably free of this effect. Despite the small size of the fluorescent label, the surface charge and hydrophobicity of the dye appear to play a key role in promoting the DNA affinity for the ZMW surface. Next, different surface passivation methods (bovine serum albumin BSA, polyethylene glycol PEG, polyvinylphosphonic acid PVPA) are quantitatively benchmarked by fluorescence correlation spectroscopy to determine the most efficient approaches to prevent the adsorption of Atto 647N labeled DNA. Protocols using PVPA and PEG-silane of 1000 Da molar mass are found to drastically avoid the non-specific adsorption into ZMWs. Optimizing both the choice of the fluorescent dye and the surface passivation protocol are highly significant to expand the use of ZMWs for single molecule fluorescence applications.
关键词： fluorescent dyes,Zero mode waveguide,single molecule fluorescence,DNA adhesion,surface passivation
更新于2025-09-19 17:13:59
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Reversible Charge Transfer with Singlea??Walled Carbon Nanotubes Upon Harvesting the Low Energy Part of the Solar Spectrum
摘要： Here, the ability of a novel near-infrared dye to noncovalently self-assemble onto the surface of single-walled carbon nanotubes (SWCNTs) driven by charge-transfer interactions is demonstrated. Steady-state, Raman, and transient absorption spectroscopies corroborate the electron donating character of the near-infrared dye when combined with SWCNTs, in the form of fluorescence quenching of the excited state of the dye, n-doping of SWCNTs, and reversible charge transfer, respectively. Formation of the one-electron oxidized dye as a result of interactions with SWCNTs is supported by spectroelectrochemical measurements. The ultrafast electronic process in the near-infrared dye, once immobilized onto SWCNTs, starts with the formation of excited states, which decay to the ground state via the intermediate population of a fully charge-separated state, with characteristic time constants for the charge separation of 1.5 ps and charge recombination of 25 ps, as derived from the multiwavelength global analysis. Of great relevance is the fact that charge-transfer occurs from the hot excited state of the near-infrared dye to SWCNTs.
关键词： doping,charge transfer interactions,noncovalent functionalization,near-infrared dyes,carbon nanotubes
更新于2025-09-19 17:13:59
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BCl3-Activated Synthesis of COO-BODIPY Laser Dyes: General Scope and High Yields under Mild Conditions
摘要： A general and straightforward method for the synthesis of COO-BODIPYs from F-BODIPYs and carboxylic acids is established. The method is based on the use of boron trichloride to activate the involved substitution of fluorine, which leads to high yields through rapid reactions under soft conditions. This mild method opens the way to unprecedented laser dyes with outstanding efficiencies and photostabilities, which are difficult to obtain by the current methods.
关键词： COO-BODIPY,Laser Dyes,Mild Conditions,High Yields,BCl3-Activated Synthesis
更新于2025-09-19 17:13:59